sgribnee



2 SheetsSheet 1.

(No Model.)

0. E. SGRIBNER. TELEPHONE EXCHANGE APPARATUS.

AAA 4- Patented Dec. 9, 1890.

(No Model.) 2 Sheets-Sheet 2.

C. E. SGRIBNER.

TELEPHONE EXGHANGE APPARATUS.

No. 442,146. Patented Dec. 9, 1890. 4 i

UNTTnn STATES PATENT OFFICE.-

CIIARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE \VES"ERN ELECTRIC COMPANY, OF SAME PLACE.

TELEPHONE-EXCHANGE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 442,146, dated December 9, 1890.

Application filed December 10,1888- Serial No. 293,165. (No model.)'

To all whom it may concern: from the battery is sent through the indi Be it known that I, CHARLES E. SCRIBNER, vidual annuueiator, while on operating the a citizen of the United States, residing at Chitelephone-switch the two branches are united cago, in the county of Cook and State of Illiin metallic circuit; the combination, with the nois, have invented a certain new and useful telephone-line extending from ground at the 5 Improvement in 'lelephone-Exchange Appacentral office through a battery to terminals, ratus, (Case 181,) of which the following is a one on each switchboard, and thence to the full, cl ar, concise, and exact description, refsubscribers station, and thence back to testerence being had to the accompanying drawterminals, one on each switch board, of

(O ings, forming a part of this specification. switching apparatus at the subscribers sta- 6o Myinvcntion relates to telephone-exchanges tion for forming a ground connection for the in which metallic circuits are employed; and battery, or uniting the telephone-line through its object is to provide apparatus which shall the subscribers station in metallic circuitto mit of looping the different lines together connect the battery to the said test-terminals;

without including any unnecessary resistance the combination, with the telephone-line ex- 6 in the talking-circuit. tending from ground at the central oiiice My invention as herein described is espethrough a battery to terminals, one on each cially adapted for use in exchanges having switch-board, and thence to the subscribers only a moderate number of suljiscribers -say station, and thence back to test-terminals,

less than one thousand-in which multiple one on each switch-board, of switching ap- 7o switclrboards are not required. Certain feaparatus at the subscribers station for formtures of my invention shown herein have ing a ground connection for the battery, or been heretofore described and claimed in my uniting the telephone-line through the sub application, Serial No. 291,658, filed Novemscribers station in metallic circuit to connect ber 23, 188$,executed November 17,1S88,for the battery to the said test-terminals, and 1nultiple-switch-board system. In said applitesting apparatus for determining the prescation one feature consists of the use of 0011- once or absence of batteryeurrent at said densers, one being placed in one of the eontest-terminals at the different boards to denecting-cords and the other in circuit with termine whether the line is in use. Such 30 the operators telephone to prevent a falsespecific matter is therefore disclaimed as to test signal. this application.

In my application, Serial No. 291,658, iiled My invention as described herein requires November 23, 1888, for telephone-exchange no test-circuits, and hence the condensers are apparatusIhave describedand claimed a medispensed with. My invention herein con- 35 tallic telephone-line circuit consisting of two sists of metallic telephone-circuits, each probranches, one branch being normally convided with two branches, one branch being nected with ground at the subscribers stanormally closed at the subscribers station tion and thence through the subscribers bell and open at acontact or terminal of the switch to the telephone-switch, and thence to the or connecting device upon the switchboard,

4o central office, said branch being connected while the other branch is normally open at 0 with the test portion of a socket on each of the subscribers station and connects with antwo or more switch-boards and being norother terminal of the switch or connecting inallyopeinwhile the other branch,being nordevice upon the switch-board, and extends mally open at the subscribers station, exfrom said terminal through an annuneiator,

tends to the otherterminals of the same sockpreferably constructed to operate as a self-in- 9 3 ets on said switch-boards, and thence through duction coil, and thence through a battery to an annunciator and a battery to ground, in ground at the central oflice, a key being procombination with the telephone-switcl1 and a vided in this branch at the subscribers staground-key at the subscriber's station, wheretion for closing the same to ground to operate 50 by on depressing the grounding-key current the individual annunciator.

LII

, ing constructed to act as self-induction coils.

My invention is illustrated in the accompanying drawings, in which- Figure 1 is a diagram showing three subscribers stations, each connected with the switch-board at the central office with a pair of loop-plugs and their cords, and the operators telephone and calling apparatus upon the switchboard, the metallic circuits of two of said stations being looped together by means of plugs and cords. Fig. 2 is an illustrative diagram of the circuits of four subscribers stations, each connected through its individual annunciator at the central office and through a common ground-wire containing a battery, two of said stations being shown looped together.

Like parts are indicated by similar letters of reference throughout the different figures.

In Fig. 1 the circuits of station 3 are shown in their normal condition, the telephone resting upon the switch. The circuit of branch a may be traced from ground through the bell to the telephone-switch and thence to socket or terminal I) of the switch-board, the branch a being shown open at terminalb. Branch 0 is shown open at the upper contact of the switch and may be traced through the telephone and transmitter to terminal (2 upon the switch-board, and thence through the annunciatorf, and thence to the ground-wire g, including the battery h. By means of a key 2' at station 3 branch 0 may be closed to ground, thus closing battery 7L through the annunciatorfto operate said annuneiator, thus notifying the central office of the call.

The operator may call up any subscriber by inserting one of the loop-plugs in the socket of the subscriber wanted and connect.- ing the generator with the branch, which is normally closed at the subscribers stationthat is to say, in case of station 3 the operator, by inserting a plug in the socket con sisting of terminals I) 6, would close the sleeve of the plug to terminal I), and thus by depressing key 70 or 76*, as the ease might be, would send current through the bell at station 3. Stations 1 and 2 are shown connected together for conversation by means of the loop-plugs Z m and the cords connecting said plugs together. It will be observed that the strand n is connected with the sleeve of plug Z and with the tip of plug 012, while the strand 0, which connects with the tip of plug Z, extends to the sleeve of plug m. Each plug is provided, as before stated, with two terminals, one terminal being upon the sleeve or shank of the plug and the other terminal being the tip of the plug. This is shown in detail in the sectional View of plug Z. The sleeve of the plug when inserted, as shown, in a socket of any line makes connection with the normally-open terminal of the socket, while the tip is closed to the terminal of the socket, which is provided with a branch connection through the annunciator and battery to ground. Thus, as more clearly shown in Fig. 2, the normally-open branch 1) of the line of station 1 is connected with the normallyelosed branch q of station 2 through strand a, while the normally-closed branch q of theline of station 1 is connected through strand 0 with the normally-open branch 2) of the line of station 2-that is to say, the open branches of any two lines are reciprocally connected, respectively, with the closed branches orlimbs of said lines-t-hat is to say, as before stated, open branch 1) is connected with closed branch (1 and closed branch q is connected with open branch 1). The talking-circuit thus formed includes only the telephones of the respective subscribers. Moreover, the two sides of the metallic circuit thus formed will be found branched each through a different coil to a colnmon line including battery,and thence to ground at the central office. By means of a loop-switch rthe operators telephone may be bridged into the circuit between the strands n 0, when desired. Vhen the subscribers are through talking, each one on hanging up his telephone operates the individual annunciator of the other, thus indicating that the conversation is finished.

My invention admits of various modifications, which would readily suggest themselves to those skilled in the art, and I therefore do not limit myself to the constructions shown.

Having thus described my invention, I claim as new and desire to secure by Letters Paten t- 1. The combination, with two subscribers stations, of their metallic-circuit telephonelines looped together to form a single metallic circuit for conversation free of resistance, except the telephones, the different sides of said metallic circuit being provided with a branch circuit, each such branch circuit containing the individual. annunciator of its line, each annunciator constructed to operate as a self-induction coil, and each of said branch circuits being connected to a ground branch, including a battery.

2. The combinatiomwith a switch-board, of telephone-lines connected therewith, said telephone-lines each consisting of two branches, one branch being normally closed at the sub scribers station and connected through the bell and switch of the station and extending to one terminal of the line upon the switchboard, while the other branch is normally open at the subscribers station and extends through the telephone at said station to the corresponding terminal upon the switch board, from which terminal it is connected ICC.

through an annuneiator and a battery to ground, and switching apparatus at the central office adapted to loop together any two of said telephone-lines, the open terminals of the two lines being reciprocally connected with the grounded terminals of the other, whereby a talking-circuit is formed which includes the resistance of no eleetromagnet coils except those of the telephone, while the different sides of said circuits are balanced through ground branches, including, respectively, the individual annunciators of the lines.

3. The loop-plugs connected with flexible cords, the two strands of said cords being each connected diagonally with the different terminals of said plugs, a switching device, and a telephone adapted to be bridged across said strands, substantially as and for thepurpose specified.

4. A telephone line consisting of two branches, one branch, as branch a, extending through the signal-bell and telephone-switch of the subscribers station, and thence to a normally-open terminal, as terminal Z), upon the switelrboarchthe other branch, as branch 0, being normally open at the subscribers station and extending through the telephone to a terminal c, corresponding with terminal b, said terminal 0 being connected through an individual annuneiator f to a ground branch g, including battery, and a key 1 connected with branch 0 at the subscribers station, and switching and signaling apparatus at the central office, whereby the subscriber may call the central ofiice or the central office the subscriber at will, substantially as and for the purpose specified.

5. A metallic-circuit telephone-line consisting of two branches, one branch being grounded at the subscribers station through the subscribers bell and the other branch being normally open at the subscribers switch, the said grounded branch being normally open at the central offiee and the other branch being eonneeted through a switch and an an nuneiator at the central oflice to a wire containing a battery, in combination with a circuit-closing device between the bell and the bell contact of a telephone-switch for closing the branch containing the bell to the side of the circuit including the individual annuneiator and battery, whereby the subscriber on operating said circuit-closing device may throw down the individual annuneiator, substantially as described.

In witness whereof I hereunto subscribe my name this 1st day of December, A. D. 1888.

CHARLES E. SCRIBNER. Wit-n esses:

GEORGE P. BARTON, ELLA. EDLER. 

